Rotation Stop Device

This application claims priority to German Patent Application No. 20 2024 102 761.2 filed on May 28, 2024, which is incorporated by reference herein in its entirety.

The invention relates to a rotation stop device for a rotatably mounted shaft, having a stationary stop body and a transmission which converts the rotational movement of the shaft into a linear movement of a driven element relative to the stop body, and having a stop element which can be moved by the driven element into a stop position in which it bears against the stop body.

Such a rotational stop device is known from DE 10 2020 126 785 U1, in which the stop element is a spring element which is held non-rotatably on the shaft and is elastically deflected into the stop position by the driven element when the end of the range of motion of the driven element is reached. The fact that the stop blocks the rotational movement of the shaft in this way limits the mechanical load to which the transmission is subjected at the moment of hitting the stop body.

It is an object of the invention is to provide a rotation stop device that can withstand higher torques.

According to the invention, this object is achieved by coupling the stop element to the shaft in a rotationally fixed and axially displaceable manner by means of a linear guide.

The linear guide stabilizes the stop element and reduces the bending moment acting on this stop element during the impact.

Advantageous embodiments and further embodiments of the invention are given in the sub-claims.

In one embodiment, the transmission is a spindle drive with a spindle seated fixedly on the shaft and a nut, which is in threaded engagement with the spindle, as the driven element.

The stop body can be arranged on or in an end wall of a housing that accommodates the transmission. The stop element can be arranged axially displaceable on the spindle so that it can be displaced by the driven element, i.e. the spindle nut, in the direction of the stop position. The stop element can have one or more projections that are guided in the linear guide and whose free ends strike against an associated stop body in the stop position. The linear guide can be formed by a guide disk that is wedged onto the shaft in a rotationally fixed manner and has openings in which the projections are precisely guided. In this case, the torque is mainly or even exclusively (if the stop element itself is not held non-rotatably on the spindle) transmitted to the stop element through the guide disk. The axial distance between the guide disk and the stop elements can be kept relatively small so that no high bending moment acts on the projections.

A spring element can be arranged between the stop element and the guide disk, which spring element elastically pretensions the stop element in the direction of the driven element so that the stop element is safely released from the stop position when the driven element moves away from the stop bodies. At the same time, the spring element can be used to limit the distance by which the stop element can move away from the guide disk.

Optionally, each stop element can be associated with a ramp surface that is adjacent to the stop element in the circumferential direction and rises at least to the level of the stop element. When the stop element is rotated in the direction opposite to the stopping direction, the free ends of the projections run onto the ramp surfaces and are thus pushed away from the stop bodies at least far enough to move freely past the stop bodies. If the stop element is then rotated again in the opposite direction, the projections will not hit the stop bodies again until the stop element has been moved back in the stop direction by the driven element. In this way, the function of the rotation stop device can be maintained even if the spring element breaks.

The rotation stop device shown inhas a pot-shaped housing, which is closed by a coverand through which a rotatably mounted shaftpasses coaxially. The housingaccommodates a transmission, which is formed by a spindlefirmly keyed onto the shaftand a nut in threaded engagement with the spindle as a driven element.

The housinghas two guide stripson the inner surface of its circumferential wall, which are embraced by fork-shaped projectionsthat project from the outer circumferential edge of the driven element. In this way, the driven elementis prevented from rotating relative to the housing, while axial movement is permitted.

On both sides of the driven element, two mutually mirror-image stop elementsare arranged on the spindle, each of which has two diametrically opposed projections. The projectionsof each stop element engage through openings of a guide disk, which is keyed to the shaftin a rotationally fixed manner. The projectionsare guided in the openings of the guide diskwith the least possible play, so that a linear guide is formed for movement of the stop elementsin the axial direction of the shaft. Two stop bodiesare arranged on the bottom of the housingand on the coverrespectively, which form stops for the free ends of the projectionsin one direction of rotation of the shaftand the stop elements.

In, the left of the two stop elementsis in its stop position, in which the projectionsare in contact with the stop bodies. On the left-hand side, only the upper stop elementcan be seen, which is located behind the associated projection. The other stop body is located on the front side of the sectional plane inand is therefore not visible.

On the right-hand side in, the stop elementsare arranged in such a way that they limit the rotational movement of the unit consisting of shaft, spindle, stop elementsand guide disksin the opposite direction.

Each of the two guide disksis provided with a spring elementwhich surrounds the shaftwith an annular base and has six radially projecting arms which pre-tension the associated stop elementin the direction away from the guide disk. The arms of the spring elementsare arranged at an angle offset from radial arms of the guide disksthat carry the projections. The stop elementat the right side ofis held by the spring elementin a position in which the projectionsare retracted into the openings of the guide disk, so that they cannot strike against the stop bodies. In the view in, the arms of the spring elementare partially covered by the arms of the guide disk. Retaining pinsare attached to the stop elementin such a way that, together with the base of the stop element, they form six insertion pockets in which the free ends of the arms of the spring elementengage. In this way, the stop elementis held by the spring elementin the axial position in which the spring element is relaxed.

On the inside of the cover,shows a rampthat runs in the circumferential direction and rises towards the stop bodyand adjoins it in the circumferential direction.

A further spring elementand a further rampare also present in mirror image on the left-hand side in. On the left-hand side in, the stop elementis held in its stop position by the spring element. The spring elementis supported on a beadof the driven elementand is thus held in a tensioned, flattened configuration.

shows the device in a sectional view along line II-II in. The sectional plane passes through the two projectionsand the parts of the rampsdirectly adjacent to them. All other components inside the housing are covered by the guide diskkeyed onto the shaftand are therefore only indicated by dashed lines in. In particular, one can see the six arms of the spring elementas well as the outline shape of the driven elementwith the fork-shaped projections, which embrace the guide strips. The apex of the beadis also shown.

In, the shape of one of the rampscan be seen in a development.

shows the device in the same sectional view as in, but in a state in which the driven elementhas been moved by the spindleto the opposite end of this spindle and now holds the spring elementon the right inand the right stop elementconnected to it in the stop position for the corresponding opposite direction of rotation. The stop elementslimit the rotation in the direction in which the lower projectionmoves away from the viewer.

If the shaft is turned in the direction opposite to the stop direction in the state shown in, the projectionsof the right-hand stop elementdetach from the stop bodiesand run onto the ramps. As a result, the stop element is also moved away from the guide diskindependently of the action of the spring element, so that the projectionsretract into the openings of the guide disk. The slope of the rampis dimensioned so that the axial movement of the stop elementis not faster than the axial movement of the driven element. The right-hand spring elementreturns to its relaxed position () and supports the movement of the stop element.

As the spindle continues to rotate, the left stop elementis brought back into its stop position by the beadof the driven elementpressing centrally on the arms of the spring element, and these push the stop elementto the left with their free ends against the spring force until the condition shown inis finally reached again.

The leverage ratio on the spring elementis dimensioned so that the contact radius of the beadof the driven elementand the contact radius on the stop elementare approximately in a ratio of 1:2, thus generating a significant increase in stroke on the stop element. (1 mm axial bead movement generates 2 mm axial travel of the stop element).

The rotation stop device shown here can be used, for example, as a steering stop in a vehicle with steer-by-wire steering and also wherever a rotational movement that involves more than one revolution (360°) needs to be limited. In the case of the steering stop, the shaftis the steering shaft and the housingis positively coupled in the direction of rotation to a steering system housing of the vehicle, which is not shown. The rotation stop device then prevents the steering shaft from being rotated endlessly in one and the same direction, which would lead to overstressing of the electrical cables that connect the switches arranged on the steering wheel to stationary vehicle components.

In a modified embodiment, not shown, an impact absorber can be provided between the stop bodiesand the projections, for example in the form of a specially shaped spring body or a metallic cushion, which absorbs the impact when the stop position is reached.